Aaslid R. Transcranial Doppler Sonography. Springer, Wien, pages 39-50, 1989.
Fullxc3xa9r R. Advances in soft computing: introduction to neuro-fuzzy systems. Physica-Verlag, Berlin, 2000.
Nelkon M. and Parker P. Advanced Physics. Heinemann educational books Ltd, London, pages 895-966, 1971.
Not applicable.
Not applicable.
The present invention relates to transcranial Doppler probe device in general and in particular to a device for mounting transcranial Doppler probes on a patient""s head and automatically insonating the cerebral vessels.
Transcranial Doppler (TCD) Sonography is an imaging technique that uses Doppler ultrasound principle to measure cerebral blood flow in basal cerebral arteries. The basic principles for common clinical applications are detailed in a book edited by Aaslid R, entitled xe2x80x9cTranscranial Doppler Sonographyxe2x80x9d and published by Springer, Vienna, dated 1989, on pages 39 through 50. However, one major problem that limits the use of TCD for long-term clinical and ambulatory monitoring in medical practice and research is the positioning of the transcranial Doppler ultrasound transducer to ensure steady ultrasound signals. In clinical practice the operator typically locates the Doppler signal by manipulating the probe over the appropriate cranial temporal acoustic windows. Once the TCD signals are found the operator fixes the probe in position and optimizes the signal quality before locking it at the best probe-to-vessel angle. The probe is then held in place by a stabilization device usually an elastic headband. Slight head movements could change the probe-to-vessel angle and cause the loss of TCD signals. This will necessitate manipulating the probe to locate the Doppler signals again by a trained operator, leading to cumbersomeness, long examination time and disruption of data acquisition protocols.
Prior art of currently in use TCD probe assemblies employ mechanisms that lock the ultrasound transducer in place and means to manually adjust the angulation of the TCD probe. U.S. Pat. No. 5,390,675 disclosed a method and apparatus comprising a TCD probe assembly which includes a TCD transducer, a pedastal, means for adjusting the angulation of the TCD probe in the pedastal and means for securing the pedastal to a patient""s head. However, patent ""675 is operator dependent incase of motion artifacts (such as coughing, yawning, biting etc). It has previously been suggested to provide a TCD probe fixation that allows continuous TCD monitoring. U.S. Pat. No. 5,070,880 discloses a probe housing stabilization device for supporting a transcranial Doppler probe against the temporal bone of the head. The device employs a generally planar, rigid member having an opening therein. The member has perforations onto which an adhesive is applied to secure it in place and the opening receives the probe thereby positioning it in place adjacent on the temporal bone. The ""880 patent provides a rigid device and again lacks the flexibility of self-regulation in case of motion artifacts. U.S. Pat. No. 6,261,231 B1 discloses a hands-free ultrasound probe holder with a receptacle comprising of probe securing means, however, does not offer automatic probe position and self-regulation. U.S. Pat. No. 5,058,592 discloses an adjustable mountable TCD probe device that incorporates a Velcro fastening means to provide support and an infinite number of fastening positions. The device of ""592 patent again lacks flexibility of automatic probe repositioning and self-regulation incase of shifts induced by motion artifacts. There have been attempts to determine the position of a probe relative to the body and means of adjusting the position to correct for errors responsive to a direct representation of the angular probe position. For example, U.S. Pat. No. 5,891,034 discloses a system for indicating the position of a surgical probe in the x, y, and z directions. The probe is rotated and tilted using information from a computer analysis to determine the body position. However, similar limitations as mentioned above apply to the ""034 patent. U.S. Pat. No. 5,121,744 illustrated a transcranial Doppler probe incorporated into a pilot or astronaut helmet that uses a motorized device to locate cerebral vessels using the three orthogonal coordinates. However, the ""744 patent involves a relatively heavier apparatus not applicable in everyday conditions and may also lack the required level of automated responsiveness necessary for involuntary motion induced artifacts.
There remains, therefore a need for a TCD probe system which provides automatically adjustable probe positions as effective substitute to manual probe repositioning in case of shifts induced by motion artifacts, and effective stabilization when optimized signals are obtained with feedback loops in a self-regulatory manner driven by an artificial intelligent system. In other words, there is required an artificial intelligent transcranial Doppler (i-TCD) probe for probe positioning in an automatic self regulating manner that is operator independent after the initial setup.
The principal objects of the present invention are a method and apparatus comprising a i-TCD probe assembly which includes a TCD transducer, bi-temporal probe hanger, cylindrical probe housing with inner wiring, probe cylindrical base with coil, probe roller balls, spring system, a removable handle and software program for adjusting the angulation of the TCD probe and a microprocessor operatively connected to the transcranial Doppler device.
The bi-temporal probe hanger is designed to allow the insertion of both probes therein into a hole provided above the temporal acoustic windows above the zygomatic arch. The hanger rests on the center of the head, the mastoid bone and the zygomatic arch from both sides, providing a support base on bone surfaces that do not have significant mobility of overlying skin and are not affected by involuntary movement artifacts induced by coughing, jaw movement etc. The hole into which the TCD probe is inserted is modified such that the cylindrical probe housing adapts to the entire range of the space overlying the posterior, middle and anterior temporal acoustic windows with the flexibility to select the best position for insonation. The TCD transducer is affixed to a probe cylindrical base with coil that in turn is inserted into a cylindrical probe housing with inner wiring. The inner wiring provides a means to generate electromotive force for angulations of the probe and also to read the position of the probe within the housing. The latter is determined using the principle of electromagnetic induction arising between the inner wiring of the housing and the coil on the probe cylindrical base. The principles of electromagnetic induction are described in basic physics textbooks such as that by Nelkon M. and Parker P. titled xe2x80x9cAdvanced Physicsxe2x80x9d published by Heinemann educational books Ltd, London, pages 895-966, 1971. The transducer cable is affixed on the air-filled inner probe cylindrical base. The probe roller balls provide means for increased degree of freedom of movement of the probe in all three x, y, and z planes. The perpendicular spring system is fitted to the probe cylindrical base for providing a force perpendicular to a patient""s head in order to improve the coupling of the probe to the skin. A lever system is derived comprising the lever as the roller balls balancing the weights of the transducer and the perpendicular pressure from the skin on one hand and the probe cylindrical base with the transducer cable and the perpendicular force from the spring system on the other, with the balance tilted in any desired direction by application of electromotive force on a set of inner wiring in the cylindrical probe housing. A software program is provided for setting the desired angulations of the probe. A removable handle is fitted to the probe cylindrical base for manually adjusting the angulations of the probe in order to xe2x80x98teachxe2x80x99 the software program to xe2x80x98learnxe2x80x99 the multiplicity of positions to find the cerebral vessels and also to select the optimal position to set threshold values for the Doppler and spectral signals. The set threshold values are used in a feedback loop to optimize the probe position.